Relation between Pro and PE + agent?

Is DEVONagent considered to be part of DEVONthink Pro?  Is it entirely separate?  Agent appears to be mostly included within think Pro.  Am I wrong?  What is the upgrade path from DEVONthink PE + DEVONagent to DEVONthink Pro?  I am about to register and am trying to decide what to register.

DEVONagent and DEVONthink (Pro/Personal) are completely independent products and DEVONagent (or similar functionality) is no part of DEVONthink Pro.

Upgrading to DEVONthink Pro from DEVONthink PE + DEVONagent is equal to upgrading from DEVONthink PE as you’re only upgrading DEVONthink but not DEVONagent.